Astilbe looks rusty
Astilbe, also called false spirea, is an herbaceous perennial which means the foliage is naturally dying down this time of year. Yours doesn’t look vigorous, though. Perhaps we can troubleshoot shoot issues with your plants and if not know exactly what is happening, at least give some steps you can take to improve your landscape health. How did you prepare the soil before planting? What year did you plant? What was there before, and did you change paths or dig drainage or other remodeling? How have you cared for it since (type of irrigation, mulch, fertilizer). Is there weed barrier used? Herbicide for weeds? Provide a few photos with wider views to allow comparisons between plants, paths, and sun exposure.